Your crawl space door is rotting. Here's why — and why the replacement shouldn't be plywood.

Plywood is layers of wood veneer glued together. Moisture wicks up from the soil into the bottom edge, the layers swell and separate, and rot moves upward from there. Meanwhile humidity cycles make the panel expand and contract until it warps out of flat — which is why a door that "still has some life in it" won't close right anymore. Paint slows this down; nothing stops it. Pressure-treated plywood resists rot longer, but it swells and warps the same as any wood, and a warped door doesn't seal no matter how rot-resistant it is.

A rotted or gapped crawl space door isn't just ugly from the driveway. It lets in moisture that feeds mold and rots framing, humid summer air and cold winter air that your floors pass straight upstairs, and animals — mice, snakes, raccoons — looking for exactly the shelter a gap provides. What's under your house doesn't stay under your house.

It's the natural move — cheap, familiar, done in an afternoon. It's also how you end up doing this again in a few years, because the new plywood inherits the same soil, the same humidity, and usually the same out-of-square opening the old door couldn't seal against. If your opening has shifted even slightly (most have), a flat homemade panel leaks air from the day it goes up.

The alternative is a door made from something that can't rot: solid 3/4-inch PVC, built to your opening's actual measurements, mounted on a frame rebuilt with pressure-treated lumber — wood for the bones, PVC for the door — and sealed. That's the whole trade we're in, and it's why our doors carry a 15-year warranty.